Use ne_map_track_number_to_index in nestegg_track_seek (from https://bugzilla.mozilla.org/show_bug.cgi?id=792935)
Merge pull request #9 from sjhworkman/master

Use ne_map_track_number_to_index in nestegg_track_seek (from https://bugzilla.mozilla.org/show_bug.cgi?id=792935)